Conventionally, the throw-away cutting tip (cutting insert) described in JP 2005-503934 A (Patent Document 1) has been known as an example of a cutting insert used for machining. The cutting insert described in Patent Document 1 includes a cutting edge, a nose, and a wiper. The wiper includes a curved segment that has a convex curved shape and is adjacent to the nose, and a flat segment that has a linear shape and is adjacent to the nose via the curved segment.
When machining is performed using the cutting insert described in Patent Document 1 and the cutting insert is fed in a direction parallel to the flat segment, unevenness of the machined surface of a work material can be minimized by the flat segment having a linear shape. Nevertheless, under processing conditions in which the cutting insert is fed in a direction inclined with respect to the linear wiper having a linear shape, as in sinking machining, the machined surface is finished using both the cutting edge and an edge of the flat segment having a linear shape. As a result, it can be difficult to adequately minimize the unevenness of the machined surface of the work material by the wiper.
An object of the present invention is to provide a cutting insert not readily affected by processing conditions and capable of increasing the smoothness of a machined surface of a work material.